After the ANSARI XPRIZE for totally privately funded vehicle capable of manned suborbital prizes and the new GOOGLE LUNAR XPRIZE for landing and shortly operating a privately funded rover on the Moon - after that I could imagine a Mars-oriented XPRIZE.

Recent news say that NASA explictly will do a manned Mars mission in 2031 - the vehicle towards Mars will be mounted in LEO by a few ARE 5-launches.

So what about a WTN XPRIZE for mounting together in LEO a small unmanned vehicle funded privately only that will have to fly to the Moon, orbit it 10 times and returns to Earth then?

Such a prize - to be established three years after the GOOGLE LUNAR XPRIZE is won for example - might result in reductions of costs of NASA's concept in comparison to the ISS (the news quoted vaguely say that the martian vehicle will weigh nearly as much as the ISS.